The invention relates to a lifting sling assembly comprising a textile lifting sling. The lifting sling defines a longitudinal direction and a webbed direction perpendicular to the longitudinal direction, and comprises a work surface region and a loop region. The lifting sling assembly further includes a reinforcement disposed on at least one of the edges and the surface of the lifting sling for protecting the lifting sling from abrasion. The reinforcement comprises a textile overlay at least partially surrounding the lifting sling at at least one of the work surface region and the loop region thereof.
Lifting slings of this kind are discussed in DIN (German Industrial Standard) 61360, dated March 1986, at Part 1 (concerning terms, dimensions, and impact types) and at Part 2 (concerning safety requirements and testing). By definition, reinforcements on the lifting sling comprise additional material permanently bonded to the lifting sling, for instance by stitching.
The invention relates in particular to lifting slings of the kind classified in versions 2N (concerning woven slings including a reinforcement) and 4N (concerning plaited slings including a reinforcement), and in form B (concerning slings with loops), in the systematic overview of lifting sling forms and embodiments on page 3 of DIN 61360, at Part 1. These reinforcements serve to protect against abrasion, especially in the area of the heavily strained lifting sling regions, such as the end loops.
Conventionally, a strip of textile material stitched on the lifting sling in the especially strained areas thereof is used as abrasion protection. For example, in a known manner, a reinforcing strip can be wrapped around the entire lifting sling in the region of the end loop of the lifting sling, and be stitched to the lifting sling. Particularly with relatively wide lifting slings, the stitched-on reinforcement in the area of the end loop has the further effect of reducing the effective sling width to approximately one-third the sling width in the region of the work surface. This width reduction in the end loop region is done in such a way that the lifting sling has at least one side edge wrapped (doubled) a direction around a longitudinal axis of the sling. In this wrapped state, the reinforcement is placed around the end loop region of the lifting sling and stitched thereto. As a result, the reinforcement has the further effect of permanently maintaining the width reduction in the region of the end loops of the sling.
The aforementioned standards prescribe that the same material as the webbing or other suitable material be used for the reinforcement, especially in the region of the end loops. In a conventional manner, a belt textile can be used that is bonded to the lifting sling as a textile overlay for the reinforcement.
For permanent fixation of reinforcements to the lifting sling, it is appropriate for their textile structure to be adequately stretchable in the region bonded to the lifting sling and thus to be adapted to the lifting sling expansion to be expected during use. These demands for stretchability of both the reinforcement fabric and the bonding of the lifting sling are somewhat contradictory to the function of abrasion protection, however. Good stretchability and good manipulability of the reinforcement when it is bonded to the lifting sling, and the avoidance of creasing which is harmful during use, require a limitation of the wall thickness of the reinforcing fabric as well. This kind of wall thickness limitation impairs the durability and effectiveness of the abrasion protection.